1. Field of the Invention
The present invention relates to an apparatus for imaging a stereoscopic image, and an apparatus for displaying the stereoscopic image, more particularly, a head-mounted apparatus for displaying a stereoscopic image capable of viewing a stereoscopic image by leading different images on right and left eyes of a viewer.
The present invention also relates to a stereoscopic image recording and/or reproducing apparatus.
2. Related Art Statement
It is well known that a reception of stereoscopic information in binocular stereoscopic vision is dominant by means of binocular parallax. (See, For example, "Magazine of Television Society, Vol. 41, No. 7, PP. 604.about.609, 1987"). The stereoscopic feeling obtained by the binocular stereoscopic vision has an effect when an object is present in a distance of about 1 m.about.100 m, but the stereoscopic feeling obtained by a vergence angle has an effect when the object is present in a distance of 1 m.about.10 m.
Hitherto, as a most simple method of imaging an object stereoscopically, a method of simultaneously imaging an object by arranging two cameras in parallel in such a manner that a distance between optical axes of the two cameras (hereinafter, referred to as basic line length) is separated by an interpupillary distance, has been well known. In this method, in order to emphasize a stereoscopic feeling, the basic line length is often made long in case of imaging a stereoscopic image.
Japanese Patent Application Publication No. 3,199/93 discloses a stereoscopic imaging apparatus using two video cameras. In this stereoscopic imaging apparatus, provision is made of image conditioning means for making imaging conditions of two video cameras equal, and a stereoscopic effect adjusting mechanism for adjusting a crossing position of optical axes of both video cameras, the crossing position of optical axes of both video cameras is made coincident with the position of the object by operating a drive motor with the stereoscopic effect adjusting mechanism based on the focussing adjusting data of the both video cameras.
Japanese Patent Application Publication No. 39,836/92 discloses a stereoscopic imaging apparatus using two stereoscopic vision television cameras and one television camera for image processing. In this stereoscopic imaging apparatus, provision is made of a monitor for displaying images from the image processing television camera, a control device for making a target point on the monitor and an image center of the monitor coincident with, a camera parallax angle monitor for making image centers of two stereoscopic vision television cameras and its target point coincident with, a smooth adjusting mechanism for adjusting an image from the stereoscopic vision television camera on the monitor picture plane in such a manner that a horizontal length of the object including the target point becomes constant, thereby obtaining a stereoscopic vision of a working object in an automating of camera operation.
In the above conventional example, the crossing of optical axes of two cameras is performed by driving the camera itself mechanically, but Japanese Patent Application Opened No. 276,395/90 discloses as another crossing method, the feature that the optical axes of two imaging optical systems are crossed by rotating a prism of wedge type.
Also as an apparatus for displaying an image stereoscopically, a display of a system using binocular parallax has been well known. In this system using binocular parallax, there are a time division system for alternately opening and closing right and left eyes with a shatter, and a two eyes system for displaying right image and left image independently. Particularly, a head-mounted display (HMD) using a LEEP optical system as a two eye system is disclosed in SPIE Vol.1256, p. 210 (1990). In this HMD, liquid crystal display and an ocular optical system are provided in a goggle in correspondence with right and left eyes, respectively, and right and left image signals including binocular parallax are supplied to the right and left liquid crystal displays, respectively, thereby displaying an image stereoscopically.
Japanese Patent Application Opened No. 281,891/93 discloses other head-mounted stereoscopic image display apparatus, in which liquid crystal display (LCD) and magnifying lenses are provided on right and left eyes of a viewer, respectively, and a frame for supporting these LCDs and lenses is provided in such a manner that right and left images formed on the front of face of the viewer by the magnifying lenses are coincident with each other, thereby performing a stereoscopic viewing with binocular parallax.
Generally, such an image display apparatus must be constructed in such a manner that a vergence angle and a diopter are coincident with each other in order not to cause physical disorder feeling, so that the above image display apparatus is also constructed in such a manner that the vergence angle and the diopter are coincident with each other in a predetermined conditions.
As a further stereoscopic image displaying apparatus, Japanese Patent Application Opened No. 95,490/92 discloses a stereoscopic image displaying apparatus in which two dimensional figure corresponding to each of plural cross-sectional positions in three dimensional image to be displayed is generated by a CRT and a vibrating directional screen, thereby displaying three dimensional image having a depth by this vibrating directional screen.
As described above, it is important for the imaging of the stereoscopic image to adjust optical axes and imaging conditions in two cameras. However, in the stereoscopic imaging apparatus disclosed in Japanese Patent Application Publication Nos. 39,836/92 and 3,199/93, a motor is used on the outer side of a camera body in order to adjust the crossing position of optical axes of the two video cameras. Particularly, the stereoscopic imaging apparatus disclosed in Japanese Patent Application Publication No. 39,836/92 has to use image processing television camera and the monitor for displaying its image in addition to two video cameras, so that a problem that whole apparatus becomes large arises. Moreover, the adjusting speed becomes slow in comparison with the adjusting speed of focussing and smoothing of the imaging optical system.
In contrary to this, in the stereoscopic imaging apparatus described in Japanese Patent Application Opened No. 276,395/90, the crossing position of optical axes of two imaging optical systems is optically adjusted, so that adjusting of the crossing position can be performed speedily than that of former stereoscopic imaging apparatus. However, the stereoscopic feeling felt by human under natural conditions can be obtained with following three functions, i.e. binocular parallax, binocular vergence and adjusting function, interactively, but in conventional stereoscopic imaging apparatus including the above examples, only the information of binocular parallax can be obtained, so that practical stereoscopic feeling can not be fully reproduced.
Even in the above stereoscopic image display apparatus, also, the binocular parallax is only utilized, so that similar problem as in the above stereoscopic image display apparatus arise, physical disorder feeling is caused in viewing of the stereoscopic image, and fatigue feeling becomes increased during long time viewing, and thus, if physical disorder feeling becomes large fusion of stereoscopic image can not be obtained.
Moreover, the above example does not consider the following point that at the time of stereoscopic image viewing, the vergence angle is changed by the contents of image (dimension of object to be viewed in the image, distance from eyes or the like), for example, if the object placed over long distance is viewed, the vergence angle becomes small and if the object placed by short distance is viewed, the vergence becomes large, and thus the diopter is fixed so far as the vergence angle is changed in accordance with the contents of the object to be viewed, so that the vergence angle and the diopter can not be coincided with each other unconditionally, and thus physical disorder feeling due to uncoincidence of the vergence angle and the diopter can not be decreased.
Moreover, when in the above example the stereoscopic image is viewed, as shown in FIG. 34, for stereoscopic display, image signals for right eye (hereinafter, referred to as right image signal) are inputted to a liquid crystal display (LCD) 701R to display the image for right eye (hereinafter, referred to as right image) on the LCD 701R, this right image is projected onto a right eye 703R of the viewer through an ocular lens 702R. Image signals for left eye (hereinafter, referred to as left image signal) is inputted to a liquid crystal display (LCD) 701L to display the image for left eye (hereinafter, referred to as left image) having parallax to the right image on the LCD 701L, this left image is projected onto a left eye 703L of the viewer through an ocular lens 702L. In this case, when the same object is displayed on a point A and a point B on the LCD 701L and LCD 701R, respectively, the object displayed on the point A is seen as in a point D and the object displayed on the point B is seen as in a point C, and corresponding image is formed at infinite distance as shown at left eye optical system. In such a condition, a pint (diopter) of eyes is unfocused at infinite distance so long as the object is seen as in the points C and D, so that the viewer feels physical disorder feeling.
When LCDs 701R and 701L are moved to the position shown in FIG. 1 by dotted lines, the image is formed on a plane H as shown in the right optical system and the pint of eyes is unfocused for the object shown at point C, so that the above physical disorder feeling can be canceled. However, even when the object shown at the point D is seen, the pint of eyes is unfocused at the plane H, so that the physical disorder feeling can not be canceled under any conditions.